partial boil vs full boil

[bigkevj]

i see you all talk about full bol and partial boil. can you explain the differences please?

 

[ChrisS]

Sure, pretty simple stuff really.

The difference is how much wort is boiling in the brew bettle. For a 5 gallon batch full boil you would boil the hops, water, and malt till you have close to 5 gallons. In a partial boil you would boil the water malt and hops in a smaller quantity, say 3 gallons, and then add more water to the wort in the fermenter. Partial just meaning a fraction of the final wort size.

 

[southern brewer]

another difference being when you do a partial boil, the cold water you add after the wort has cooled has oxygen in it, whereas the part of the wort you boil is devoid of oxygen. Oxygen helps yeast to thrive and reproduce better. Doing a partial boil usually means that you don't have to shake the hell out of the wort or use an aeration stone to try to diffuse oxygen into the wort. From what I have experience with my beer and my brother's beer, the beer also comes out a bit smoother on partial boils.

 

[malkore]

in response to southern brewer: the cold water that brings you to 5 gallons total volume is supposed to be pre-boiled and cooled, which removes the oxygen.
otherwise you need to sanitize that un-boiled water with campden tabs, or your risk introducing wild yeasts/molds/bacteria from your tap water (even filtered water can have these 'bugs')

a full vs. partial boil shouldn't yield a smoother beer, unless you're talking about the hop bitterness and flavor. in a partial boil, you have a higher gravity wort, and that actually 'fights' the efficiency of the hops. (this is why some extract brewers do a late extract addition...adding half the malt in the last 10 mins of the boil...so they get more bang outta their hops).

 

[homebrewer_99]

in response to southern brewer: the cold water that brings you to 5 gallons total volume is supposed to be pre-boiled and cooled, which removes the oxygen.
otherwise you need to sanitize that un-boiled water with campden tabs, or your risk introducing wild yeasts/molds/bacteria from your tap water (even filtered water can have these 'bugs')

a full vs. partial boil shouldn't yield a smoother beer, unless you're talking about the hop bitterness and flavor. in a partial boil, you have a higher gravity wort, and that actually 'fights' the efficiency of the hops. (this is why some extract brewers do a late extract addition...adding half the malt in the last 10 mins of the boil...so they get more bang outta their hops).

Only partially true.

I do 1.5 gal boils. My top off water is filtered tap water. I've never pre-boiled, etc. Just straight from the tap...no additives.

In Charlie P's book there's a chart for hop utilization that I use. It says that 1 lb of malt in 1 gal of water with 1 oz of hops extract 30% of the bitterness for the hops boiled for 60 mins. That's the maximum extraction level. If you boil for 90 mins it's still 30%.

This above process is what I use. I boil 1.5 gals with 1 lb DME, and the full amount of bittering hops called out in the recipe. Boil 45 mins. Remove from heat. Add and dissolve remaining DME, return to heat, boil 15 mins. I've also just steeped for 15 mins, but have not determined if there is a difference either way.

In one experiment I reduced the boil to 30 mins and doubled up on the hops. This extracts the same amount of bitterness as a 60 min boil but with the shortened time the flavor is also extracted from the hops. So one hop is used for both at the same time. Strange, huh? Interestingly, when the brew is young you can taste the hop flavor and the bitterness balances the brew well. When you age the brew for a month or so the flavoring hops dissipate in about 1 month.

I've been brewing this way for many years and have no plans on changing my process...but will continue to experiment as always.

 

[malkore]

interesting info indeed. probably the most confusing aspect of brewing is that you can do it 20 ways and still get a great beer in the end!

 

[CharlieB]

a helpful website for me was www.tastybrew.com they have full recipe calculators that will tell you the approximate outcome of your beers. same thing with www.beertools.com

 

[Phan71]

in response to southern brewer: the cold water that brings you to 5 gallons total volume is supposed to be pre-boiled and cooled, which removes the oxygen.
otherwise you need to sanitize that un-boiled water with campden tabs, or your risk introducing wild yeasts/molds/bacteria from your tap water (even filtered water can have these 'bugs')

Really? I didn't know this. I've just been using straight tap water to top off my batches! I guess I've just been lucky. Chicago water tends to be pretty clean, but sometimes has a slight chlorine smell to it. I should look into using campden tablets, I understand that they primarily are for de-chlorinating, but they kill organisms, too?

 

[DeathBrewer]

i use tap water to top off all my batches and i've never had a problem...good water here in oakland. it's probably not a problem for you either... you may wish to look into filtering your water, tho, just to be sure.

 

[mrk305]

.... unfiltered tap water here too, and no problems.